package p2000;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main2034人见人爱A减B {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int n = scanner.nextInt();
            int m = scanner.nextInt();

            if (n == 0 && m == 0) {
                break;
            }

            List<Integer> setN = new ArrayList<>(n);
            List<Integer> setM = new ArrayList<Integer>(m);
            List<Integer> result = new ArrayList<Integer>(m + n);

            while (n-- > 0) {
                setN.add(scanner.nextInt());
            }

            while (m-- > 0) {
                setM.add(scanner.nextInt());
            }

            result.addAll(setN);
            result.removeAll(setM);

            if (result.size() == 0) {
                System.out.println("NULL");
            } else {
                Collections.sort(result);

                for (Integer aResult : result) {
                    System.out.print(aResult + " ");
                }

                System.out.println();
            }
        }
    }

}
